Microelectronic component assemblies employing lead frames having reduced-thickness inner lengths

ABSTRACT

The present disclosure suggests various microelectronic component assembly designs and methods for manufacturing microelectronic component assemblies. In one particular implementation, a microelectronic component assembly includes a microelectronic component, at least two leads, and at least two bond wires. Each of the leads may have a reduced-thickness inner length adjacent terminals of the microelectronic component and a body having an outer surface spaced farther from the microelectronic component than a bond surface of the inner length. Each of the bond wires couples the microelectronic component to one of the leads and has a maximum height outwardly from the microelectronic component that is no greater than the height of the outer surface of the lead.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims foreign priority benefits of SingaporeApplication No. 200301338-0 filed Mar. 4, 2003, the entirety of which isincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to microelectronic component assemblies.In particular, aspects of the invention relate to microelectroniccomponent assemblies employing lead frames and methods of manufacturingmicroelectronic component assemblies employing such lead frames. Certainembodiments of the invention provide packaged microelectronic componentassemblies.

BACKGROUND

Semiconductor chips or dies typically are manufactured from asemiconductor material such as silicon, germanium, or gallium/arsenide.An integrated circuit or other active feature(s) is incorporated in thedie adjacent one surface, often referred to as the “active surface,” ofthe die. The active surface typically also includes input and outputterminals to facilitate electrical connection of the die with anothermicroelectronic component.

Since semiconductor dies can be degraded by exposure to moisture andother chemical attack, most dies are encapsulated in a package thatprotects the dies from the surrounding environment. The packagestypically include leads or other connection points that allow theencapsulated die to be electrically coupled to another electroniccomponent, e.g., a printed circuit board. Typically, the leads extendlaterally outwardly in a flat array that is part of a lead frame. Leadedpackages include a semiconductor die, which may be attached to the leadframe either by seating the die on a die paddle or attaching the diedirectly to the leads, e.g., via a die attach adhesive in aleads-on-chip attachment. Some or all of the terminals of thesemiconductor die then may be electrically be connected to leads of thelead frame, e.g., by wire bonding. The connected lead frame and die maythen be encapsulated in a mold compound to complete the packagedmicroelectronic component assembly. The leads extend outwardly from themold compound, allowing the features of the semiconductor die to beelectrically accessed. Finally, the lead frame will be trimmed andformed into a desired configuration of electrically independent leads.

FIG. 1 schematically illustrates a conventional packaged microelectroniccomponent assembly 10. This microelectronic component assembly 10includes a semiconductor die 20 having an active surface, which bears anarray of terminals 24, and a back surface 26. This microelectroniccomponent assembly 10 is a conventional leads-on-chip package with aplurality of leads 30 a and 30 b attached to the active surface 22 ofthe die 20 by adhesive members 35 a and 35 b. Typically, the innerlength 32 a of each of a series of first leads 30 a will be attached toa first adhesive member 35 a. The inner length 32 b of each of a set ofsecond leads 30 b are attached to the die 20 by a second adhesive member35 b. The inner ends of the first leads 30 a may be spaced from theinner ends of the second leads 30 b. This defines a terminal gap 34between the ends of the leads 30 through which the terminals 24 of thedie 20 can be accessed by a wire bonding machine or the like.

The microelectronic component assembly 10 also includes a plurality ofbond wires 40. A first set of bond wires 40 a may extend from individualterminals 24 of the die 20 to the inner ends 32 a of the first leads 30a. Similarly, a series of second bond wires 40 b may extend from otherterminals 24 in the terminal array to the inner ends 32 b of the secondleads 30 b. Typically, these bond wires 40 are attached using wirebonding machines that spool a length of wire through a capillary. Amolten ball may be formed at a protruding end of the wire and thecapillary may push this molten ball against one of the terminals 24,thereby attaching the terminal end 42 of the wire 40 to the die 20. Thecapillary will then be moved laterally in a direction away from the lead30 to which the wire 40 will be attached (referred to as the reversemotion of the capillary) then a further length of the wire will bespooled out and the lead end 44 of the wire 40 will be attached to theinner end 32 of one of the leads 30. The reverse motion of the capillaryis required to bend the wire into the desired shape to avoid unduestress at either the terminal end 42 or the lead end 44.

The need to move the capillary in the reverse direction to form the bendin the wire 40 requires significant clearance between the terminal end42 and the inner ends of the leads 30. This increases the width W of theterminal gap 34. This, in turn, increases the length of each of the bondwires 40 and often requires an increased loop height L of the wire 40outwardly from the active surface 22 of the die 20. By way of example, aconventional microelectronic component assembly 10 may include adhesivemembers 35 having a thickness of about 4 mils and a lead frame 30 havinga lead frame of about 5 mils. In such a microelectronic componentassembly 10, the width W of the terminal gap 34 commonly will be on theorder of 100 mils (about 2.5 mm) or more. (FIG. 1 is merely a schematicillustration and is not drawn to scale; the thicknesses of many of theelements of the assembly 10 have been exaggerated for purposes ofclarity.) Conventional wire bonding machines commonly yield a maximumloop height L in such an assembly 10 of about 10–14 mils.

As noted above, most commercial microelectronic component assemblies arepackaged in a mold compound 50. The mold compound 50 typicallyencapsulates the die 20, the adhesive members 35, the bond wires 40, andthe inner lengths 32 of the leads 30. A remainder of the leads 30extends laterally outwardly from the sides of the mold compound 50. Inmany conventional applications, the mold compound 50 is delivered usingtransfer molding processes in which a molten dielectric compound isdelivered under pressure to a mold cavity having the desired shape. Inconventional side gate molds, the mold compound will flow from one sideof the cavity to the opposite side. As the front of the moltendielectric compound flows along the terminal gap 34 under pressure, itwill tend to deform the wires. This deformation, commonly referred to as“wire sweep,” can cause adjacent wires 40 to abut one another, creatingan electrical short. Wire sweep may also cause one of the wires 40 tobridge two adjacent leads, creating an electrical short between the twoleads. These problems become more pronounced as the wire pitch becomessmaller and as thinner wires 40 are used. For example, the stiffness ofa 20 μm diameter wire is only about 40% that of a 25 μm wire and a 15 μmdiameter wire is only about 13% as stiff as a 25 μm wire. Sincesemiconductor dies 20 are continually decreasing in size and theterminals 24 are getting closer and closer to one another, wire sweep inconventional packaged microelectronic component assemblies 10 is likelyto cause even more problems in the future.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a conventional packagedmicroelectronic component assembly.

FIG. 2 is a schematic cross-sectional view of a microelectroniccomponent subassembly in accordance with one embodiment of theinvention.

FIG. 3 is a schematic cross-sectional view of the microelectroniccomponent subassembly of FIG. 2 after the addition of bonding wires.

FIG. 4 is a schematic cross-sectional view of a packaged microelectroniccomponent assembly in accordance with one embodiment of the inventionthat incorporates the microelectronic component subassembly of FIG. 3.

FIG. 5 is a schematic cross-sectional view of a packaged microelectroniccomponent assembly in accordance with another embodiment of theinvention that incorporates the microelectronic component subassembly ofFIG. 3.

FIG. 6 is a schematic cross-sectional view of a microelectroniccomponent assembly in accordance with yet another embodiment of theinvention that incorporates the microelectronic component subassembly ofFIG. 3.

FIG. 7 is a schematic cross-sectional view of a stacked microelectroniccomponent assembly of still another embodiment of the invention.

FIG. 8 is a schematic cross-sectional view of a stacked microelectroniccomponent assembly in accordance with an alternative embodiment of theinvention.

FIG. 9 is a schematic cross-sectional view of a microelectroniccomponent assembly in accordance with an alternative embodiment of theinvention.

FIG. 10 is a schematic cross-sectional view of a microelectroniccomponent assembly in accordance with a further embodiment of theinvention.

FIG. 11 is a schematic cross-sectional view of a stacked microelectronicassembly in accordance with yet another embodiment of the invention.

DETAILED DESCRIPTION

A. Overview

Various embodiments of the present invention provide variousmicroelectronic component assemblies and methods for formingmicroelectronic component assemblies. The terms “microelectroniccomponent” and “microelectronic component assembly” may encompass avariety of articles of manufacture, including, e.g., SIMM, DRAM,flash-memory, ASICs, processors, flip chips, ball grid array (BGA)chips, or any of a variety of other types of microelectronic devices orcomponents therefor.

A microelectronic component assembly in accordance with one embodimentincludes a microelectronic component, at least two leads, and at leasttwo bond wires. The microelectronic component has an active surface andan array of terminals carried on the active surface. The leads may beattached to the active surface of the microelectronic component, witheach of the leads having an elongate body and a reduced-thickness innerlength that is disposed adjacent the terminals of the microelectroniccomponent. The body of each lead has a first thickness and an outersurface at a first height outwardly from the active surface of themicroelectronic component. The inner length has a second thickness and abond surface at a second height outwardly from the active surface of themicroelectronic component. The first thickness is greater than thesecond thickness and the first height is greater than the second height.Each of the bond wires may 1) electrically couple one of the terminalsof the microelectronic component to the bond surface of one of theleads, and 2) have a maximum height outwardly from the active surface ofthe microelectronic component that is no greater than the first height.

Another embodiment of the invention provides a method of manufacturing amicroelectronic component assembly. In accordance with this method, anactive surface of a microelectronic component is juxtaposed with firstand second leads. Each of the first and second leads has a body having afirst thickness and an inner length having a second thickness that isless than the first thickness. The first and second leads have innerends opposed to one another across a terminal gap. The first and secondleads may be attached to the active surface of the microelectroniccomponent with a linear array of terminals carried by the active surfaceextending longitudinally through the terminal gap. The body of each ofthe first and second leads may have an outer surface adjacent its innerlength that is spaced a body height outwardly from the active surface ofthe microelectronic component. A first bond wire may be attached to afirst terminal of the array and to the inner length of the first leadand a second bond wire may be attached to a second terminal of the arrayand to the inner length of the second lead. The first and second bondwires may each have a maximum height outwardly from the active surfacethat is less than the body height.

A microelectronic component assembly in accordance with anotherembodiment comprises first and second microelectronic components; first,second, and third leads; and first, second, and third bond wires. Thefirst microelectronic component has an active surface that carries afirst terminal and a second terminal. Each of the first and second leadsis attached to the active surface of the first microelectronic componentand has an elongate body and a reduced-thickness inner length that isdisposed adjacent the terminals of the microelectronic component. Thebody has an outer surface at a first height outwardly from the activesurface of the first microelectronic component and the inner length hasa bond surface at a second height outwardly from the active surface ofthe first microelectronic component. The first height is greater thanthe second height. The first bond wire electrically couples the firstterminal to the bond surface of the first lead and the second bond wireelectrically couples the second terminal to the bond surface of thesecond lead. Each of the first and second bond wires has a maximumheight outwardly from the active surface of the first microelectroniccomponent that is no greater than the first height. The secondmicroelectronic component has a back surface oriented toward the activesurface of the first microelectronic component and an active surfaceoriented away from the first microelectronic component. The secondmicroelectronic component is attached to the outer surface of the bodyof each of the first and second leads. The third bond wire electricallycouples a third terminal carried on the active surface of the secondmicroelectronic component to the third lead.

Another embodiment of the invention provides a microelectronic componentassembly that includes a microelectronic component, a set of firstleads, a set of second leads, first and second bond wires, a dielectricmatrix, and an array of conductive structures. The microelectroniccomponent has an active surface carrying an array of terminals. Each ofthe first leads has an inner length adjacent the array of terminals andan elongate body extending laterally outward in a first direction fromthe inner length. Each of the second leads has an inner length adjacentthe array of terminals and an elongate body extending laterally outwardin a different second direction from the inner length. The body of eachof the first and second leads has a first thickness and an outer surfaceat a first height outwardly from the active surface of themicroelectronic component. The inner length of each of the first andsecond leads has a second thickness and a bond surface at a secondheight outwardly from the active surface of the microelectroniccomponent. The first thickness is greater than the second thickness andthe first height is greater than the second height. The first bond wireelectrically couples a first terminal of the array of terminals to thebond surface of one of the first leads. The second bond wireelectrically couples a second terminal of the array of terminals to thebond surface of one of the second leads. Each of the first and secondbond wires has a maximum height outwardly from the active surface of themicroelectronic component that is no greater than the first height. Thedielectric matrix covers the first and second bond wires and at least aportion of the inner length of each of the first and second leads. Thedielectric matrix may have a maximum height outwardly from the activesurface of the microelectronic component that is no greater than thefirst height. Each of the conductive structures may be carried on and inelectrical contact with the outer surface of the body of one of thefirst leads or one of the second leads.

A microelectronic component assembly in accordance with yet anotherembodiment of the invention includes a microelectronic component, atleast two leads, and at least two bond wires. The microelectroniccomponent has an active surface and an array of terminals carried on theactive surface. The leads are attached to the active surface of themicroelectronic component, with each of the leads having an elongatebody, a reduced-thickness inner length that is disposed adjacent theterminals of the microelectronic component, and an intermediate lengthdisposed between the body and the inner length. The body has a firstthickness and an outer surface at a first height outwardly from theactive surface of the microelectronic component. The intermediate lengthhas a second thickness and an intermediate surface at a second heightoutwardly from the active surface of the microelectronic component. Theinner length has a third thickness and a bond surface at a third heightoutwardly from the active surface of the microelectronic component. Thesecond thickness is less than the first thickness but greater than thethird thickness. The second height is less than the first height butgreater than the third height. Each of the bond wires electricallycouples one of the terminals of the microelectronic component to thebond surface of one of the leads. In one implementation, each bond wirehas a maximum height outwardly from the active surface of themicroelectronic component that is no greater than the second height.

Another embodiment of the invention provides a microelectronic componentassembly that includes first and second microelectronic components,first and second leads, and first, second, and third bond wires. Thefirst microelectronic component has an active surface that carries afirst terminal and a second terminal. Each of the first and second leadsis attached to the active surface of the first microelectronic componentand has an elongate body, a reduced-thickness inner length, and anintermediate length. The elongate body of each of the leads has an outersurface at a first height outwardly from the active surface of the firstmicroelectronic component. The inner length is disposed adjacent theterminals of the microelectronic component and has a bond surface at asecond height outwardly from the active surface of the firstmicroelectronic component. The first height is greater than the secondheight. The intermediate length of each of the leads is disposed betweenthe body and the inner length of that lead. The intermediate length hasa mounting surface at a third height outwardly from the active surfaceof the first microelectronic component. The third height is less thanthe first height but greater than the second height. The first bond wireelectrically couples the first terminal to the bond surface of the firstlead and the second bond wire electrically couples the second terminalto the bond surface of the second lead. The second microelectroniccomponent has a back surface oriented toward the active surface of thefirst microelectronic component and an active surface oriented away fromthe first microelectronic component. The back surface of the secondmicroelectronic component is attached to the mounting surface of theintermediate length of each of the first and second leads. The thirdbond wire electrically couples a third terminal carried on the activesurface of the microelectronic component to a third lead.

For ease of understanding, the following discussion is subdivided intofive areas of emphasis. The first section discusses microelectroniccomponent assemblies employing reduced-thickness lead frames inaccordance with selected embodiments of the invention. The secondsection describes aspects of microelectronic component assemblies havingstacked microelectronic components in other embodiments of theinvention. The third section discusses other microelectronic componentassemblies employing reduced-thickness lead frames in accordance withselected alternative embodiments of the invention. The fourth sectiondescribes alternative microelectronic component assemblies havingstacked microelectronic components. Finally, the fifth section outlinesmethods in accordance with other aspects of the invention.

B. Microelectronic Component Assemblies Employing Reduced-thickness LeadFrames

FIGS. 2 and 3 schematically illustrate microelectronic componentsubassemblies in accordance with selected embodiments of the invention.These microelectronic components are referred to herein as subassembliesprimarily because they are unlikely to be sold commercially in thisfashion and instead represent an intermediate stage in the manufactureof a commercial device, e.g., the packaged microelectronic componentassembly 100 of FIG. 4.

Turning first to FIG. 2, the microelectronic component subassembly 101shown therein includes a microelectronic component 110 and a pluralityof leads 120. The microelectronic component 110 has an active surface112 and a back surface 116. The active surface 112 carries an array ofterminals 114. In one embodiment (not shown), the terminals 114 arealigned along a longitudinal midline of the microelectronic component110. In the illustrated embodiment, the terminals 114 are arranged in alongitudinally extending array in which the terminals 114 are staggeredalong either side the midline of the microelectronic component. As isknown in the art, such a staggered arrangement can facilitate a smallerwire pitch, increasing the maximum number of terminals 114. Arrays inwhich the terminals 114 are more widely distributed on the activesurface 112 may be used instead.

The microelectronic component 110 may comprise a single microelectroniccomponent or a subassembly of separate microelectronic components. Inthe embodiment shown in FIG. 2, the microelectronic component 110 istypified as a single semiconductor die. In one particularimplementation, the microelectronic component 110 comprises a memoryelement, e.g., SIMM, DRAM, or flash memory. In other implementations,the microelectronic component 110 may comprise an ASIC or a processor,for example.

During manufacture, the leads 120 may comprise a portion of a lead framethat includes dozens of leads, including a set of first leads 120 a anda set of second leads 120 b. The inner edges 125 a of each of the firstleads 120 a may be aligned with one another at a location extendingalong one side of the array of terminals 114. The inner edges 125 b ofthe second leads 120 b likewise may be aligned with one another at alocation extending along the opposite side of the array of terminals114. This defines a terminal gap 132 between the aligned inner edges 125a of the first leads 120 a and the aligned inner edges 125 b of thesecond leads 120 b. As explained below, aspects of the microelectroniccomponent assembly 101 allow the width W of the terminal gap 132 to besubstantially smaller than the terminal gap width W encountered inconventional designs such as that shown in FIG. 1.

Each of the leads 120 may be attached to the microelectronic component110 by means of an adhesive member 135. In particular, a confrontingsurface 130 a of each of the first leads 120 a may be attached to theactive surface 112 of the microelectronic component 110 by a firstadhesive member 135 a. Similarly, a confronting surface 130 b of each ofthe second leads 120 b may be attached to the active surface 112 of themicroelectronic component 110 by a second adhesive member 135 b. In oneembodiment, each of the adhesive members 135 comprises a length of aconventional die attach tape, e.g., a polyimide film such as KAPTON. Inanother embodiment, each adhesive member 135 comprises a quantity of athermoplastic resin or a curable epoxy.

Leads of conventional lead frames, e.g., the leads 30 in FIG. 1,typically have a constant thickness along their length. The leads 120 ofFIG. 2 have a reduced-thickness inner length 122 and a body 126 that isthicker than the inner length 122. The lateral length of the innerlength 122 can be varied significantly. In one embodiment, for example,each inner length extends a distance from the inner edge 125 to the body126 of at least about 7 mils (about 175 μm) and may be one inch (about22 mm) or longer.

The body 126 a of each of the first leads 120 a has an outer surface 128a spaced a first height H₁ from the active surface 112 of themicroelectronic component 110. The body 126 b of each of the secondleads 120 b may have an outer surface 128 b that is spaced the samefirst height H₁ from the active surface 112. Hence, the outer surfaces128 of the leads 120 may be generally coplanar within a common plane Pspaced a height H₁ from the active surface 112. The inner length 122 aof the first lead 120 a has a bond surface 124 a and the inner length122 b of each of the second leads 120 b has a bond surface 124 b. Eachof the bond surfaces 124 may be positioned at a second height H₂ fromthe active surface 112. The first height H₁ is greater than the secondheight H₂, defining a step height H_(s) between the bond surface 124 andthe body outer surface 128 of each of the leads 120.

The relative dimensions of these heights H₁, H₂, and H_(s) may be variedto meet the needs of a particular application. In the embodiments shownin FIG. 2, the first height H₁ is the sum of the thickness of theadhesive members 135 and the thickness of each of the lead bodies 126.In one particular implementation, the adhesive member 135 comprises adie attach tape having a thickness of about 2–5 mils, e.g., about 4mils. The leads 120 may comprise part of a lead frame formed from a thinmetal foil. Such lead frames typically have a thickness on the order ofabout 4–15 mils. In some embodiments of the invention, the thickness ofthe lead bodies 126 is toward the lower end of that range, e.g., about4–8 mils. In one particular embodiment, the lead bodies 126 have athickness of about 5 mils. When the leads 120 are attached to themicroelectronic component 110 by the adhesive members 135, the resultantfirst height H₁ in certain embodiments is between about 6 mils and about12 mils. In one particular implementation, the adhesive member 135 has athickness of about 4 mils and the lead bodies 126 have a thickness ofabout 5 mils, yielding a first height H₁ of about 9 mils.

In one embodiment, the step height H_(s) is at least about 1 mil (about25 microns). The inner length 122 desirably has a thickness of at leastabout 2 mils (about 50 microns), so the step height H_(s) may be about 2mils less than the thickness of each lead body 126. In the exemplaryembodiment noted above wherein the lead bodies 126 have a thickness ofabout 5 mils and the adhesive members 135 are about 4 mils thick, thestep height H_(s) may be about 3 mils, positioning the bond surfaces 124of the inner lengths 122 at a second height H₂ of about 6 mils from theactive surface 112. In one embodiment, the step height H_(s) is 40% ormore of the thickness of the lead body 126. In one particularembodiment, the step height H_(s) is about 50–60% of the thickness ofthe lead body 126.

In the embodiment shown in FIG. 2, there is a sharp change in thicknesswhere the lead body 126 adjoins the inner length 122. This is notnecessary; a more gradual transition between the bonding surface 124 andthe outer surface 128 can be used instead. The method in which the innerlength 122 is provided with its reduced thickness is not material. Thereduced-thickness inner length 122 may, for example, be created usingconventional photomask/etch processes, machine tooling, or laserablation.

FIG. 3 schematically illustrates a microelectronic component subassembly102 that incorporates the microelectronic component subassembly 101 ofFIG. 2. In particular, the device shown in FIG. 3 may comprise themicroelectronic component subassembly 101 of FIG. 2 with two or morebond wires 140 attached thereto. In the cross-sectional view of FIG. 3,only two bond wires, a first bond wire 140 a and a second bond wire 140b, are visible. The first bond wire 140 a has a terminal end 142 bondedto one of the terminals 114 of the microelectronic component 110 and alead end 144 attached to the bond surface 124 a of the first lead 120 a.The second bond wire 140 b also has a terminal end 142 attached to oneof the terminals 114 of the microelectronic component 110 and has a leadend 144 that is attached to the bond surface 124 b of the second lead120 b. A terminal length 143 of each of the bond wires 140 may bepositioned in the terminal gap 132 and extend outwardly from the activesurface 112 of the microelectronic component 110.

In the subassembly 102 of FIG. 3, each of the bond wires 140 has amaximum height L outwardly from the active surface 112 that is nogreater than the height (H₁ in FIG. 2) of the outer surfaces 128 of theleads 120. As a consequence, none of the bond wires 140 will extendoutwardly beyond the common plane P of the outer surfaces 128 of theleads 120. In FIG. 3, the maximum height L of the bond wires 140 is nogreater than the height H₁ of the common plane P, leaving the bond wires140 spaced a distance D below this common plane P. In selectembodiments, this distance D is about 0–3 mils (about 0–75 microns). Inone particular embodiment, the distance D is about 2–3 mils (about 50–75microns). In one particular embodiment, the step height H_(s) is atleast about two times the diameter of the bonding wires 140. It isbelieved that a step height H_(s) of about 2–2.5 times the thickness ofthe bonding wire 140 will provide more than adequate manufacturingtolerances to ensure that the bond wires 140 do not extend outwardlybeyond the common plane P of the outer surfaces 128 of the lead bodies126.

In accordance with different embodiments of the invention, amicroelectronic component subassembly 102 such as that illustrated inFIG. 3 may be incorporated in different microelectronic componentassemblies. FIG. 4 illustrates one particular microelectronic componentassembly 100 that is manufactured from the microelectronic componentsubassembly 102 of FIG. 3. The microelectronic component assembly 100also includes a dielectric matrix 150 that covers the bond wires 140,the microelectronic component 110, and a portion of each of the leads120, leaving an exposed portion 134 of each of the leads 120 extendinglaterally outwardly from the dielectric matrix 150. In the illustratedembodiment, the dielectric matrix 150 includes a first portion 152 thatdefines a front surface 153 of the assembly 100 and a second portion 158that defines a back surface 159 of the assembly 100. The first andsecond portions 152 and 158 may be formed during the same manufacturingstep, e.g., in a single transfer molding operation. In anotherembodiment, the first portion 152 and the second portion 158 are formedin separate manufacturing steps.

The dielectric matrix 150 may be formed of any material that willprovide suitable protection for the elements within the matrix 150. Itis anticipated that most conventional, commercially availablemicroelectronic packaging mold compounds may be useful as the dielectricmatrix 150. Such mold compounds typically comprise a dielectricthermosetting plastic that can be heated to flow under pressure into amold cavity of a transfer mold. In other embodiments, the dielectricmatrix 150 may comprise a more flowable dielectric resin that can beapplied by wicking under capillary action instead of delivered underpressure in a transfer mold.

As noted previously, terminal pitch and bond wire pitch in packagedmicroelectronic components (e.g., microelectronic component 10 ofFIG. 1) are decreasing over time. The requisite smaller wire diametersand closer spacing exacerbates the previously-noted problems associatedwith wire sweep. The microelectronic component assembly 100 of FIG. 4can reduce some of these problems. Having the bond surface 124 of theleads positioned closer to the active surface 112 of the microelectroniccomponent 110 reduces the spacing necessary for the reverse motion ofthe capillary of a wire bonding machine. This, in turn, permits theopposed inner edges 125 a and 125 b to be positioned closer to oneanother, reducing the width (W in FIG. 2) of the terminal gap 132. Incontrast to the conventional design of FIG. 1 with a terminal gap widthW of 2.5 mm or more, the width W of the terminal gap 132 in FIGS. 2–4may be 35 mils or less, e.g., 35 mils or less for 25 μm wires or 23 milsor less for 15 μm wires. Because the bond wires 140 need not extendoutwardly from the active surface 112 as far or laterally as far toreach the bonding surface 124 of the leads, the length of each of thebonding wires 140 can be materially reduced. Wire sweep increases as thebonding wires become longer. Shortening the bond wires 140, therefore,will reduce the wire sweep encountered for bond wires 140 having thesame diameter, or it may permit the use of thinner (and cheaper) bondwires 140 that experience about the same degree of wire sweep.

If the terminal gap 34 in a conventional microelectronic componentassembly 10 has too small of a gap width W, the mold compound will haveto be delivered at a higher molding pressure to ensure that the moldcompound reaches all the way to the active surface 22. In the embodimentshown in FIG. 4, the terminal gap 132 has a depth equal to the height(H₂ in FIG. 2) of the bonding surfaces 124 from the active surface 112.This reduced depth reduces the resistance of flow of mold compound downto the active surface 112 of the microelectronic component 110. Theterminal gap width W, therefore, can be reduced while still ensuringadequate fill of the terminal gap 132.

FIG. 5 schematically illustrates a microelectronic component assembly105 in accordance with a further embodiment of the invention. Most ofthe elements of the microelectronic component assembly 105 may be thesame as those illustrated in FIG. 4 and like reference numbers are usedin FIGS. 4 and 5 to indicate like elements. The primary distinctionbetween the microelectronic components 100 and 105 is that the firstportion 152 of the dielectric matrix 150 shown in FIG. 4 may beintegrally formed from a single material, whereas the first portion 152of the dielectric matrix 150 in FIG. 5 has two distinct segments. Inparticular, the first portion 152 in FIG. 5 includes a dielectric wireencapsulant 154 and an outer mold compound 155. In one embodiment, thedielectric wire encapsulant 154 is applied on the microelectroniccomponent assembly 102 of FIG. 3, then the outer mold compound 155 andthe second portion 158 of the dielectric matrix 150 may be formed in asingle transfer molding operation.

The dielectric wire encapsulant 154, if employed, desirably at leastpartially covers each of the bond wires 140. In the embodiment shown inFIG. 5, the dielectric wire encapsulant 154 substantially fills theterminal gap 132 and covers both the entire length of each of the bondwires 140 and a portion of the bond surface 124 of the lead innerlengths 122. The dielectric wire encapsulant 154 in this embodiment hasa maximum height no greater than the height (H₁ in FIG. 2) of the outersurfaces 128 of the leads 120. This may reduce the likelihood of damageto the dielectric wire encapsulant 154 during subsequent manufacturingsteps.

In another embodiment, the dielectric wire encapsulant 154 has a maximumheight that is lower than that shown in FIG. 5 and is spaced below thecommon plane P of the outer surfaces 128. In one particularimplementation (not specifically shown in FIG. 5), the dielectric wireencapsulant 154 covers the terminal length 143 of each of the bond wires140, but leaves at least some of the bond wires 140 with an exposedlength that is not covered by the dielectric wire encapsulant 154. Insuch an embodiment, the dielectric wire encapsulant 154 may not fill theterminal gap 132 and may even have a maximum height that is less thanthe height (H₂ in FIG. 2) of the bonding surfaces 124 of the leads 120.

In one embodiment, the dielectric wire encapsulant 154 is formed of amaterial that is different than the dielectric material that comprisesthe outer mold compound 155. The material selected for the dielectricwire encapsulant 154 may have a viscosity when initially applied that isless than the viscosity of the outer mold compound 155 when it isapplied. In one particular implementation, the dielectric wireencapsulant 154 comprises a curable resin that can be applied at a lowerviscosity to flow between and beneath the bond wires 140 and, if sodesired, substantially fill the terminal gap 132, but can be hardened ina subsequent curing step. One such material is commercially availablefrom Kulicke and Soffa of Willow Grove, Pa., U.S.A. under the trade nameNOSWEEP.

Using a dielectric wire encapsulant 154 such as that described above canfurther reduce the problems associated with wire sweep. If the outermold compound 155 is delivered under pressure in a transfer moldingoperation, for example, the dielectric wire encapsulant 154 will helpstabilize the bond wires 140. In the embodiment shown in FIG. 5, thedielectric wire encapsulant 154 completely encapsulates the bond wires140 so they will not be affected materially by the pressure of thetransfer molding operation. If a portion of some or all of the bondwires 140 remains exposed, covering the terminal length 143 or otherappropriate segment of each of the bond wires 140 still helps anchor thebond wires 140 in place and reduces the length of each of the bond wires140 that may be subjected to strain as the front of the mold compoundmoves through the mold cavity.

FIG. 6 schematically illustrates a microelectronic component assembly200 in accordance with another embodiment of the invention that may alsoemploy the microelectronic component subassembly 102 shown in FIG. 3.This microelectronic component assembly 200 includes a dielectric matrix210 that substantially fills the terminal gap 132 and covers the bondwires 140, the active surface 112 of the microelectronic component 110,and the bond surfaces 124 of the inner lengths 122. However, theremainder of each of the leads 120 and the remainder of themicroelectronic component 110 may remain uncovered by the dielectricmatrix 210. The dielectric matrix 210 may have a maximum heightoutwardly from the active surface 112 of the microelectronic componentthat is no greater than the height (H₁ in FIG. 2) of the outer surfaces128 of the leads 120. In the particular implementation illustrated inFIG. 6, the dielectric matrix 210 has an outer surface 216 that issubstantially coplanar with the common plane (P in FIG. 3) of the outersurfaces 128 of the leads 120. This presents the microelectroniccomponent assembly 200 with a relatively flat outer surface thatcomprises the outer surface 216 of the dielectric matrix 210 and theouter surfaces 128 of the leads 120.

If so desired, the dielectric matrix 210 may be formed integrally in asingle step, e.g., via a transfer molding process. The dielectric matrix210 shown in FIG. 6 includes a dielectric wire encapsulant 212 and anouter mold compound 214. The dielectric wire encapsulant 212 may besubstantially the same as the dielectric wire encapsulant 154 discussedabove in connection with FIG. 5. The dielectric wire encapsulant 212shown in FIG. 6 leaves a portion of the terminal gap 132 unfilled and alength of each of the bond wires 140 is not covered by the dielectricwire encapsulant. This dielectric wire encapsulant 212 may be applied ina first step and the outer mold compound 214 may be applied in a secondstep, e.g., in a transfer molding process or using gob top techniques.If so desired, any excess dielectric matrix 210 can be removed from theouter surfaces 128 of the lead bodies 126, e.g., via etching orgrinding.

The microelectronic component assembly 200 of FIG. 6 also includes anarray of conductive structures 220. Each of the conductive structures220 is carried on and is in electrical contact with the outer surface128 of one of the leads 120. In FIG. 6, these conductive structures aretypified as solder balls. Other suitable conductive structures mayinclude conductive epoxy bumps or pillars, conductor-filled epoxy, or ananisotropic “Z-axis” conductive elastomer. These conductive structures220 may be used to electrically connect the leads 120 of themicroelectronic component assembly 200 to another microelectroniccomponent, e.g., a substrate such as a printed circuit board, usingconventional flip chip or BGA techniques.

In the embodiments of FIGS. 4 and 5, each of the leads 120 includes anexposed length 134 that extends laterally outwardly beyond thedielectric matrix 150 to facilitate connection of the leads to othermicroelectronic components. In the embodiment of FIG. 6, the leads 120may be electrically coupled to another microelectronic component via theconductive structures 220. Accordingly, the leads 120 in this embodimentcan be shorter. Although leads 120 shown in FIG. 6 extend a shortdistance laterally outwardly beyond the periphery of the microelectroniccomponent 110, in another embodiment the leads 120 are trimmed so theydo not protrude beyond the periphery of the microelectronic component110, further reducing the size and profile of the microelectroniccomponent assembly 200.

The microelectronic component assembly 200 optionally includes aprotective cover 225 on the back surface 116 of the microelectroniccomponent 110. This protective cover 225 helps protect themicroelectronic component 110 during subsequent handling andmanufacturing steps. The protective cover 225 may be applied as a fluid,e.g., an epoxy, or as a polymeric tape, e.g., a polyimide tape.

C. Microelectronic Component Assemblies Having Stacked MicroelectronicComponents

The microelectronic component assemblies 100 and 200 shown in FIGS. 4and 5, respectively, are relatively low-profile assemblies including asingle microelectronic component 110. Microelectronic componentassemblies in accordance with other embodiments of the inventionincorporate two or more microelectronic components in a single package.One such microelectronic component assembly 300, illustrated in FIG. 7,incorporates the microelectronic component subassembly 102 shown in FIG.3 and adds a second microelectronic component 310. The secondmicroelectronic component 310 includes an active surface 312 bearing anarray of terminals 314 and a back surface 316. The back surface 316 isjuxtaposed with and oriented toward the active surface 112 of the firstmicroelectronic component 110. The back surface 316 of the secondmicroelectronic component 310 may be attached to the outer surfaces 128of the lead bodies 126 by a pair of adhesive members 320. The samematerials outlined above for the adhesive members 135 are likely to besuitable for the adhesive members 320.

The back surface 316 of the second microelectronic component 310 isspaced from the active surface 112 of the first microelectroniccomponent 110 by a distance equal to the height (H₁ of FIG. 2) of theouter surfaces 128 of the leads 120 and the thickness of the adhesivemembers 320. This defines an intercomponent gap 325 between the firstmicroelectronic component 110 and the second microelectronic component310.

One or more third bond wires 330 may be used to electrically couple theterminals 314 of the second microelectronic component 310 to anothermicroelectronic component, e.g., a PCB, via the leads 120. Each of thethird bond wires 330 shown in FIG. 7 includes a terminal end 332attached to one of the terminals 314 and a lead end 334 attached to oneof the leads 120. In one embodiment, at least one of the leads 120 isconnected at its inner length 122 to the first microelectronic component110 by a bond wire 140 and has a third bond wire 330 attached to itsouter surface 128. This provides a pathway for electrical communicationbetween the first and second microelectronic components 110 and 310.

The microelectronic component assembly 300 shown in FIG. 7 also includesa dielectric matrix 370 that covers the first microelectronic component110, the second microelectronic component 310, the bond wires 140 and330, and a covered length of each of the leads 120. This dielectricmatrix 370 may be formed of much the same materials and in much the samefashion as the dielectric matrix 150 of FIG. 4 or FIG. 5. The dielectricmatrix 370 shown in FIG. 7 includes a dielectric wire encapsulant 372that extends outwardly from the active surface 112 of the firstmicroelectronic component 110 no farther than the common plane (P inFIG. 3) of the outer surfaces 128 of the leads 120. This dielectric wireencapsulant 372 is directly analogous to the dielectric wireencapsulants 154 and 212 discussed previously. The remainder of theintercomponent gap 325 may be filled with a mold compound 374 that alsocovers the rest of the structures noted above. This mold compound 374may be delivered to the intercomponent gap 325 in a single transfermolding operation that also delivers the rest of the mold compound 374to encapsulate the remainder of the noted elements.

FIG. 8 schematically illustrates a microelectronic component assembly305 in accordance with another embodiment of the invention. Thismicroelectronic component assembly 305 may include all of the elementsshown in FIG. 7 and like reference numbers are used in FIGS. 7 and 8 toindicate like elements. The microelectronic component assembly 305 alsoincludes a third microelectronic component 340. This thirdmicroelectronic component 340 has an active surface 342 carrying anarray of terminals 344. A back surface 346 of the third microelectroniccomponent 340 may be attached to the back surface 116 of the firstmicroelectronic component 110 by an adhesive member 350. This adhesivemember 350 may be formed from the same types of material suitable forthe adhesive members 135 and 320 noted previously. In one embodiment,the adhesive members 135 and 320 comprise lengths of die attach tape,but the adhesive member 350 is applied as a flowable material such as acurable dielectric epoxy that can flow when squeezed between the twomicroelectronic components 110 and 340.

The third microelectronic component 340 may be electrically coupled tothe leads 120 by fourth bond wires 360. These bond wires 360 have aterminal end 362 attached to one of the terminals 344 and a lead end 364attached to the confronting surface 130 of one of the leads 120. If sodesired, each of the leads 120 may be connected to no more than one ofthe microelectronic components 110, 310 and 340. In another embodiment,though, at least one of the leads is connected to two or more of thesemicroelectronic components 110, 310 and 340. If so desired, one of theleads 120 can be connected to the first microelectronic component 110 bya bond wire 140, connected to the second microelectronic component 310by another bond wire 330, and connected to the third microelectroniccomponent 340 by yet another bond wire 360. This single lead 120 wouldpermit electrical communication between all three of the microelectroniccomponents 110, 310 and 340.

The microelectronic component assembly 305 also includes a dielectricmatrix 370. This dielectric matrix 370 is large enough to encompass notonly the first and second microelectronic components 110 and 310, butalso encompasses the third microelectronic component 340 and the fourthbond wires 360. This presents a single package that can incorporatethree separate microelectronic components 110, 310 and 340. This can beused, for example, to provide a high density memory package, in whicheach of the microelectronic components may comprise the same type ofmemory element, e.g., SIMM, DRAM, or flash memory.

As discussed above, having the bond wires 140 recessed below the commonplane P of the outer surfaces 128 of the leads 120 provides a thinner,more compact microelectronic component subassembly 102. This, in turn,allows the production of appreciably thinner microelectronic componentassemblies (e.g., 300 or 305) incorporating multiple microelectroniccomponents.

D. Alternative Microelectronic Component Assemblies EmployingReduced-thickness Lead Frames

In the microelectronic component assembly 100 of FIG. 4, a confrontingback surface 130 of each of the leads 120 is attached to the activesurface 112 of the microelectronic component 110 and the entirethickness of the microelectronic component 110 is spaced from each ofthe leads 120 by the thickness of the adhesive members 135. By employingbond wires 140 with a maximum height (L in FIG. 3) no greater than theheight (H₁ in FIG. 3) of the common plane P, the overall thickness ofthe particular microelectronic component assembly 100 shown in FIG. 4can be reduced.

FIGS. 9 and 10 illustrate reduced-thickness microelectronic componentassemblies in accordance with alternative embodiments. In each of theseembodiments, a portion of the thickness of a microelectronic componentis received within a thickness of each of the leads, thereby reducingthe overall thickness of the microelectronic component assembly.

Turning first to FIG. 9, the microelectronic component assembly 400shown therein employs a first set of leads 120 a and a second set ofleads 120 b. These leads 120 may be substantially the same as thosediscussed above in connection with FIGS. 2–4, for example, and likereference numbers are used in FIG. 9.

The microelectronic component assembly 400 includes a microelectroniccomponent 410 having a back surface 416, an active surface 412, and anarray of terminals 414 carried on the active surface 412. Themicroelectronic component 410 has a thickness between its back surface416 and active surface 412 that is greater than the step height (H_(s)in FIG. 2) of each of the leads 120.

In the embodiment of FIGS. 3 and 4, the confronting surface 130 of eachof the leads 120 is attached to the microelectronic component 110 by anadhesive member 135 and each of the bond wires 140 extends between aterminal 114 of the microelectronic component 110 and a bond surface 124of one of the leads 120. In the application of FIG. 9, however, the bondsurface 124 of each of the leads functions as a mounting surface and theconfronting surface 130 of each of the leads 120 functions as a backsurface. In particular, the active surface 412 of the microelectroniccomponent 410 may be attached to the mounting surface 124 of each of theleads 120 by an adhesive. In the illustrated embodiment, the mountingsurface 124 a of each of the first leads 120 a is attached to the activesurface 412 of the microelectronic component 410 by a first adhesivemember 135 a and the mounting surface 124 b of each of the second leads120 b may be attached to the active surface 412 of the microelectroniccomponent 410 by a second adhesive member 135 b. In one embodiment, eachof the adhesive members 135 comprises a length of a conventionaldie-attach tape. In another embodiment, each of the adhesive members 135comprises a thickness of a thermoplastic resin or a curable epoxy. Inone embodiment, these adhesive members 435 have a thickness which isless than the step height (H_(s)) in FIG. 2 of each of the leads 120. Inthe particular embodiment illustrated in FIG. 9, each of the adhesivemembers 435 has a thickness that is substantially less than the stepheight H_(s). In one particular implementation, each of the adhesivemembers 435 has a thickness of about 1 mil for a lead 120 having a stepheight H_(s) of 3 mils.

The microelectronic component assembly 400 also includes at least twobond wires 440, with each bond wire electrically coupling one of theterminals 414 of the microelectronic component 410 to the back surface130 of one of the leads 120. Hence, a first bond wire 440 a may have aterminal end 442 bonded to one of the terminals 414 of themicroelectronic component 410 and a lead end 444 that is attached to theback surface 130 a of the first lead 120 a. Similarly, a second bondwire 440 b has a terminal end 442 attached to another one of theterminals 414 of the microelectronic component 410 and has a lead end444 that is attached to the back surface 130 b of the second lead 120 b.A terminal length 443 of each of the bond wires 440 may be positioned ina gap between the inner ends of the leads 120 and extend to a heightoutwardly from the active surface 412 at least as great as the thicknessof the inner length 122 of the lead 120 to which it is attached.

In the illustrated embodiment, the outer surfaces 128 of the leads 120are generally coplanar within a common outer plane and the back surfaces130 of the leads 120 are generally coplanar within a common back plane.The active surface 412 of the microelectronic component 410 ispositioned between these two planes. The back surface 416 of themicroelectronic component 410 is spaced outwardly from the outersurfaces 128 of the leads 120. Consequently, at least a portion of themicroelectronic component 410 is received within the step height H_(s),of each of the leads 120 and the overall thickness of the combination ofthe leads 120 and the microelectronic component 410 is reduced ascompared to conventional lead-on-lead chip systems such as that shown inFIG. 1.

The microelectronic component assembly 400 of FIG. 9 also includes adielectric matrix 450 that covers the bond wires 440, themicroelectronic component 410, and a portion of each of the leads 120,leaving an exposed portion of each of the leads 120 extending laterallyoutwardly from the dielectric matrix 150. A first portion 452 of thedielectric matrix 450 defines a front surface 453 of the assembly 400and a second portion 458 of the dielectric matrix 150 defines a backsurface 459 of the assembly 400. These first and second portions 452 and458 may be formed during the same manufacturing step or in separatemanufacturing steps. The materials used for the dielectric matrix 450may be similar to those discussed above for the dielectric matrix 150 ofthe microelectronic component assembly 100 shown in FIG. 4.

FIG. 10 illustrates a microelectronic component 402 in accordance withan alternative embodiment of the invention. Many of the elements in FIG.10 are shared in the microelectronic component assembly 400 of FIG. 9and like reference numbers are used in both drawings to indicate likecomponents. One of the differences between the microelectronic componentassemblies 400 and 402 is the orientation of the microelectroniccomponent 410 with respect to the leads 120. In FIG. 9, the activesurface 412 of the microelectronic component 410 is juxtaposed with andattached to the mounting surface 124 a of the leads 120. In theembodiment of FIG. 10, the microelectronic component 410 is inverted,with the active surface 412 oriented to face outwardly in the samedirection as the outer surfaces 128 of the leads 120. The back surface416 of the microelectronic component 410 is disposed between the outerplane containing the lead outer surfaces 128 and the back planecontaining the lead back surfaces 130. Each of the bond wires 440connects one of the terminals 414 of the microelectronic component 410to the outer surface 128 of the one of the leads 120 rather than to theback surface 130 of the lead 120 as in FIG. 9.

E. Microelectronic Component Assemblies Having Stacked MicroelectronicComponents and Multi-stepped Leads

Aspects of some of the embodiments outlined above may be combined toyield alternative reduced-height electronic component assemblies withstacked microelectronic components. FIG. 11 schematically illustratesone such microelectronic component assembly.

The microelectronic component assembly 500 shown in FIG. 11 is similarin some respects to the microelectronic component assembly 305 shown inFIG. 8 and like reference numbers are used in FIGS. 8 and 11 to indicatelike elements. The leads 120 in the microelectronic component assembly305 of FIG. 8 have a single change in thickness between the body 126 andthe inner length 122. The microelectronic component assembly 500 of FIG.11 employs leads 520 with two or more changes in thickness along thelength of the lead 520. Hence, the microelectronic component assembly500 includes a set of first leads 520 a having a body 526 a, an innerlength 522 a, and an intermediate length 525 a disposed between the body526 a and the inner length 522 a. The microelectronic component assembly500 also includes a set of second leads 520 b, each of which has aninner length 522 b, an intermediate length 525 b, and an elongate body526 b. The inner length 522 of each of the leads 520 has a bond surface524 similar to the bond surface 124 of leads 120. Each of theintermediate lengths 525 may define a mounting surface 523. The bondsurface 524, mounting surface 523, and outer surface 528 (528 a and 528b being shown in FIG. 11) may all be oriented in generally the samedirection (outwardly away from the first microelectronic component 110in FIG. 11).

In the illustrated embodiment, the intermediate length 525 of each ofthe leads 520 has a thickness that is greater than the thickness of theinner length 522, but less than the thickness of the body 526 of thesame lead. Consequently, the mounting surface 523 of each of the leadsis disposed at a mounting height outwardly from the active surface 112of the first microelectronic component 110 that is greater than thecorresponding height of the bond surface 524 with respect to themicroelectronic component active surface 112, but less than the heightof the lead outer surfaces 528 outwardly from the active surface 112.

The microelectronic component assembly 500 includes a secondmicroelectronic component 511 having an active surface 512, which bearsan array of terminals 514, and a back surface 516. The active surface512 is oriented away from the first microelectronic component 110,whereas the back surface 516 is juxtaposed with, but spaced from, theactive surface 112 of the first microelectronic component 110. The backsurface 516 of the second microelectronic component may be attached tothe mounting surfaces 523 of the leads 520 by two or more adhesivemembers 535 a and 535 b. These adhesive members 535 may be formed ofmaterials similar to those discussed above in connection with theadhesive members 435 of the microelectronic component assembly 400 inFIG. 9. In one embodiment, the adhesive members 535 each have athickness that is less than the difference in height between themounting surface 523 and outer surface 528 of the lead 520 to which itis attached. As a consequence, the back face 516 of the secondmicroelectronic component 511 may be positioned at a height outwardlyfrom the first microelectronic component active surface 112 that is lessthan the corresponding height of the lead outer surfaces 528. In oneembodiment, the mounting surfaces 523 may all be at least substantiallycoplanar, juxtaposing the back surface 516 of the second microelectroniccomponent 511 generally parallel to the active surface 112 of the firstmicroelectronic component 110.

The bond wires 140 connecting the terminals 114 of the firstmicroelectronic component 110 to the bond surfaces 524 of the lead innerlengths 522 have a maximum height outwardly from the firstmicroelectronic component active surface 112 that is no greater than theheight of the back surface 516 of the second microelectronic component511 from the same active surface 112. More desirably, each of the firstset of bond wires 140 has a height less than the height of the secondmicroelectronic component back surface 516 to avoid direct contactbetween the bond wires 140 and the second microelectronic component 511.In one embodiment, each of the first set of bond wires 140 has a maximumheight outwardly from the active surface 112 which is no greater thanthe height of the mounting surfaces 523 of the leads 520. This willleave a manufacturing tolerance at least as great as the thickness ofthe adhesive members 535 joining the second microelectronic component511 to the leads 520.

In one embodiment, a dielectric wire encapsulant 372 may be disposed inthe intercomponent gap 537 between the first and second microelectroniccomponents 110 and 511. In the illustrated embodiment, the dielectricwire encapsulant 372 has a maximum height outwardly from the activesurface 112 that is less than the height of the back surface 516 of thesecond microelectronic component 511. In another embodiment, thedielectric wire encapsulant 372 may substantially fill theintercomponent gap 537.

The terminals 514 of the second microelectronic component 511 may becoupled to one or more of the leads 520 by one or more second bond wires530. In the illustrated embodiment, a terminal end 532 of each of thesecond bond wires 530 may be attached to one of the terminals 514 of thesecond microelectronic component and an opposite end of each of thesecond bond wires 530 may be attached to the outer surface 528 of one ofthe leads 520. In the illustrated embodiment, the active surface 512 ofthe second microelectronic component 511 is spaced a height outwardlyfrom the active surface 112 of the first microelectronic component 110that is greater than the corresponding height of the outer surfaces 528of the leads 520. By positioning the back surface 516 of the secondmicroelectronic component 511 below the outer surfaces 528 of the leads520, this can still reduce the height of the microelectronic componentassembly 500 as compared to the microelectronic component assembly 305shown in FIG. 8, wherein the back surface 316 of the secondmicroelectronic component 310 is spaced outwardly from the lead outersurfaces 128 by the thickness of the adhesive members 320.

The microelectronic component assembly 500 may also include a dielectricmatrix 570 that covers the first microelectronic component 110, thesecond microelectronic component 511, the third microelectroniccomponent 340, the bond wires 140, 360, and 530, and a covered length ofeach of the leads 520. The dielectric matrix 570 may be formed of muchthe same materials and in much the same fashion as the dielectric matrix150 of FIG. 4, for example. The dielectric matrix 570 desirably includesa mold compound 574, which may substantially fill the intercomponent gap537. If a dielectric wire encapsulant 372 is employed, the mold compound574 may substantially fill any remaining portion of the intercomponentgap 537 that is not filled with the dielectric wiring caps 372. Anexposed portion 534 of each of the leads 520 may extend laterallyoutwardly from the dielectric matrix 570.

F. Methods of Manufacturing Microelectronic Component Assemblies

As noted above, other embodiments of the invention provide methods ofmanufacturing microelectronic component assemblies. In the followingdiscussion, reference is made to the particular microelectroniccomponent assemblies shown in FIGS. 2–8. It should be understood,though, that reference to these particular microelectronic componentassemblies is solely for purposes of illustration and that the methodoutlined below is not limited to any particular microelectroniccomponent assembly shown in the drawings or discussed in detail above.

In one embodiment, a method of the invention may include juxtaposing anactive surface 112 of a microelectronic component 110 with leads 120 ofa lead frame. Once the leads 120 are in the desired position withrespect to the microelectronic component 110, the leads may be attachedto the active surface 112 of the microelectronic component 110 with thearray of terminals 114 extending longitudinally through the terminal gap132. In one embodiment, this attachment is accomplished via a pair ofadhesive members 135. If the adhesive members 135 each comprise a dieattach tape, the first adhesive member 135 a may be attached to theactive surface 112 along a first longitudinal side of the array ofterminals 114 and the second die attach tape 135 b may be attached tothe active surface 112 to extend longitudinally on the other side of thearray of terminals. The leads may then be brought into contact with theouter surfaces of the adhesive members 135, thereby attaching the leads120 to the microelectronic component 110.

In one embodiment, at least two bond wires 140 are used to electricallycouple the microelectronic component 110 to selected ones of the leads120. Using a conventional, commercially available wire bonding machine,a terminal end 142 of a first wire bond 140 a may be attached to one ofthe terminals 114 of the microelectronic component 110 and the lead end144 of the first bond wire 140 a may be bonded to the bond surface 124of one of the first leads 120 a. In a similar fashion, a second bondwire 140 b may be attached to a second terminal 114 of themicroelectronic component 110 and to the bond surface 124 of one of thesecond leads 120 b. In one embodiment, each of the bond wires 140 has amaximum height outwardly from the active surface 112 of themicroelectronic component 110 that is less than the height H₁ of thelead outer surface 128.

A dielectric matrix 150 may be used to protect the microelectroniccomponent subassembly 102. In the embodiment shown in FIG. 4, themicroelectronic component subassembly 102 may be positioned in atransfer mold with the microelectronic component 110 and the bond wires140 positioned in a mold cavity. A molten dielectric resin may then bedelivered under pressure to fill the mold cavity, yielding a dielectricmatrix 150 such as that shown in FIG. 4.

In the embodiment shown in FIG. 5, the dielectric wire encapsulant 154may be applied before the rest of the dielectric matrix 150. In oneparticular embodiment, the dielectric wire encapsulant 154 is deliveredas a flowable resin that can flow beneath and around the bond wires 140.In one implementation, a relatively small quantity of the dielectricwire encapsulant 154 is delivered, covering only the terminal length 143of each of the bond wires 140 and leaving a remainder of each of thebond wires 140 exposed. In another implementation, sufficient dielectricwire encapsulant 154 is delivered to cover the entire length of each ofthe bond wires 140 and a portion of the bond surface 124 of each of theleads 120. As noted previously, this dielectric wire encapsulant 154 maybe applied so it has a maximum height outwardly from the active surface112 that is no greater than the height H₁ of the outer surfaces 128 ofthe leads 120. Thereafter, the outer mold compound 155 may be appliedover the dielectric wire encapsulant 154, e.g., using a conventionaltransfer molding operation.

To form the microelectronic component assembly 200 shown in FIG. 6, theouter surface 216 of the dielectric matrix 210 may be formed at a heightno higher than the common plane P of the outer surfaces 128 of the leadbodies 126. As noted previously, the matrix outer surface 216 may besubstantially coplanar with the common plane P. This can be accomplishedby using a mold having a mold surface that is in direct contact with theouter surfaces 128 of the lead bodies 126. If necessary, any inadvertentflash coating of the dielectric matrix 210 on the outer surfaces 128 ofthe leads 120 may be removed by etching or grinding. The conductivestructures 220 may be applied to some or all of the outer surfaces 128of the leads 120 to define an array of conductive structures 220. Theconductive structures 220 may be deposited using a solder mask/etchprocess, screen printing, or any of a number of other conventionaltechniques used in depositing solder balls, conductive epoxies, andother conductive structures. If so desired, a protective cover 225 maybe applied to the back surface 116 of the microelectronic component 110,e.g., by applying a polyimide tape or the like having an adhesive on oneface to the back surface 116.

In forming a multi-component microelectronic component assembly 300 suchas that shown in FIG. 7, the back surface 316 of the secondmicroelectronic component 310 may be attached to the outer surfaces 128of the leads 120 by adhesive members 320. If a dielectric wireencapsulant 372 is to be employed, this dielectric wire encapsulant 372may be deposited in the terminal gap 132 before the secondmicroelectronic component 310 is attached to the leads 120. Once thesecond microelectronic component 310 is in place, it may be electricallycoupled to one or more of the leads 120 by one or more bond wires 330.The dielectric matrix 370 may then be formed about and between the firstand second microelectronic components 110 and 310. In one embodiment,this is accomplished by placing the microelectronic components 110 and310 and the leads 330 in a mold cavity of a transfer mold and deliveringa molten mold compound to the cavity. This mold compound desirablysubstantially fills the intercomponent gap 325 between themicroelectronic components 110 and 310. Providing a dielectric wireencapsulant 372 may be particularly useful in this embodiment as thepressures necessary to ensure that the intercomponent gap 325 isadequately filled with the mold compound 374 may otherwise produce undowire sweep.

Much the same technique used to produce the microelectronic componentassembly 300 can be used to produce the microelectronic componentassembly 305 of FIG. 8. The third microelectronic component 340 may beattached to the back surface 116 of the first microelectronic component110 by the adhesive member 350 and coupled to the leads 120 by the bondwires 360 before the dielectric matrix 370 is applied, though. Likewise,the techniques outlined above can be used to produce the microelectroniccomponent assemblies 400, 402, and 500 shown in FIGS. 9–11,respectively.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense, that is to say, in a sense of “including,but not limited to.” Words using the singular or plural number alsoinclude the plural or singular number, respectively. When the claims usethe word “or” in reference to a list of two or more items, that wordcovers all of the following interpretations of the word: any of theitems in the list, all of the items in the list, and any combination ofthe items in the list.

The above-detailed descriptions of embodiments of the invention are notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example,whereas steps are presented in a given order, alternative embodimentsmay perform steps in a different order. The various embodimentsdescribed herein can be combined to provide further embodiments.

In general, the terms used in the following claims should not beconstrued to limit the invention to the specific embodiments disclosedin the specification, unless the above-detailed description explicitlydefines such terms. While certain aspects of the invention are presentedbelow in certain claim forms, the inventors contemplate the variousaspects of the invention in any number of claim forms. Accordingly, theinventors reserve the right to add additional claims after filing theapplication to pursue such additional claim forms for other aspects ofthe invention.

1. A microelectronic component assembly comprising: a microelectroniccomponent having an active surface and an array of terminals carried onthe active surface; first and second leads attached to the activesurface of the microelectronic component, each of the leads having anelongate body and a reduced-thickness inner length that is disposedadjacent the terminals of the microelectronic component, the body havinga first thickness and an outer surface at a first height outwardly fromthe active surface of the microelectronic component, and the innerlength having a second thickness and a bond surface at a second heightoutwardly from the active surface of the microelectronic component, thefirst thickness being greater than the second thickness, and the firstheight being greater than the second height; first and second bondwires, each bond wire electrically coupling one of the terminals of themicroelectronic component to the bond surface of one of the leads andeach bond wire having a maximum height outwardly from the active surfaceof the microelectronic component that is no greater than the firstheight; and a dielectric wire encapsulant that at least partially coverseach of the bond wires and an outer mold compound that covers the wireencapsulant and a portion of each of the leads, wherein the dielectricwire encapsulant has a different composition than the mold compound;wherein the each of the leads includes an intermediate length disposedbetween the body and the inner length, the intermediate length having athird thickness and an intermediate surface at a third height outwardlyfrom the active surface of the microelectronic component, the thirdthickness being less than the first thickness and greater than thesecond thickness.
 2. The microelectronic component assembly of claim 1wherein the body of each of the leads has a confronting surface orientedtoward the active surface and the inner length of each of the leads hasa confronting surface oriented toward the active surface, theconfronting face of each body being substantially coplanar with theconfronting surface of the inner length of the same lead.
 3. Themicroelectronic component assembly of claim 1 wherein each of the bondwires has a wire diameter and the difference between the first andsecond heights is at least as great as the wire diameter.
 4. Themicroelectronic component assembly of claim 1 wherein each of the bondwires has a wire diameter and the difference between the first andsecond heights is at least twice the wire diameter.
 5. Themicroelectronic component assembly of claim 1 wherein the first heightis at least 2 mils greater than the second height.
 6. Themicroelectronic component assembly of claim 1 wherein the inner lengthsof the first and second leads are separated by a terminal gap of nogreater than 35 mils, at least one of the terminals being exposed in theterminal gap.
 7. The microelectronic component assembly of claim 6wherein the dielectric wire encapsulant extends into the terminal gapand covers at least a portion of each of the first and second leads. 8.The microelectronic component assembly of claim 6 wherein the dielectricwire encapsulant extends into the terminal gap and covers at least aportion of each of the first and second leads, the dielectric wireencapsulant having a maximum height outwardly from the active surface ofthe microelectronic component that is no greater than the first height.9. The microelectronic component assembly of claim 1 wherein thedielectric wire encapsulant covers at least a portion of each of theleads and a portion of the active surface of the microelectroniccomponent.
 10. The microelectronic component assembly of claim 1 whereinthe dielectric wire encapsulant covers at least a portion of each of theleads and a portion of the active surface of the microelectroniccomponent, and wherein the mold compound does not cover a back surfaceof the microelectronic component.
 11. The microelectronic componentassembly of claim 1 wherein the outer mold compound at least partiallycovers each of the bond wires.
 12. The microelectronic componentassembly of claim 1 wherein the dielectric wire encapsulant at leastpartially covers each of the bond wires and has a maximum heightoutwardly from the active surface of the microelectronic component thatis no greater than the first height.
 13. The microelectronic componentassembly of claim 1 wherein the dielectric wire encapsulant covers aterminal length of each of the bond wires, at least some of the bondwires having an exposed length that is not covered by the wireencapsulant.
 14. A microelectronic component assembly comprising: afirst microelectronic component having an active surface that carries afirst terminal and a second terminal; a first lead and a second lead,each of the first and second leads being attached to the active surfaceof the first microelectronic component, each of the first and secondleads having an elongate body and a reduced-thickness inner length thatis disposed adjacent the terminals of the microelectronic component, thebody having an outer surface at a first height outwardly from the activesurface of the first microelectronic component and the inner lengthhaving a bond surface at a second height outwardly from the activesurface of the first microelectronic component, the first height beinggreater than the second height; a first bond wire electrically couplingthe first terminal to the bond surface of the first lead and a secondbond wire electrically coupling the second terminal to the bond surfaceof the second lead, each of the first and second bond wires having amaximum height outwardly from the active surface of the firstmicroelectronic component that is no greater than the first height; asecond microelectronic component having a back surface oriented towardthe active surface of the first microelectronic component and an activesurface oriented away from the first microelectronic component, thesecond microelectronic component being attached to the outer surface ofthe body of each of the first and second leads; a third bond wireelectrically coupling a third terminal carried on the active surface ofthe second microelectronic component to a third lead; and a dielectricmatrix encapsulating the first and second microelectronic components.15. The microelectronic component assembly of claim 14 wherein thedielectric matrix covers the first and second microelectroniccomponents; the first, second, and third bond wires; and a coveredlength of the first and second leads.
 16. The microelectronic componentassembly of claim 14 wherein the dielectric matrix covers the first andsecond bond wires.
 17. The microelectronic component assembly of claim14 wherein the dielectric matrix comprises a dielectric wire encapsulantand a bulk mold compound, the dielectric wire encapsulant substantiallyfilling a portion of the intercomponent gap and covering at least aportion of each of the first and second bond wires, the bulk moldcompound substantially filling a remainder of the intercomponent gap.18. The microelectronic component assembly of claim 14 furthercomprising a third microelectronic component having a back surface andan active surface, the back surface of the third microelectroniccomponent being attached to a back surface of the first microelectroniccomponent.
 19. The microelectronic component assembly of claim 18further comprising a fourth bond wire electrically coupling a fourthterminal carried on the active surface of the third microelectroniccomponent to a fourth lead of the lead frame.
 20. A microelectroniccomponent assembly comprising: a microelectronic component having anactive surface that has first and second edges and carries an array ofterminals; a set of first leads attached to the active surface, eachfirst lead having an inner length adjacent the array of terminals and anelongate body extending laterally outward in a first direction from theinner length to an outer end proximate the first edge of the activesurface; a set of second leads attached to the active surface, eachsecond lead having an inner length adjacent the array of terminals andan elongate body extending laterally outward in a second direction fromthe inner length to an outer end proximate the second edge of the activesurface, the second direction being different from the first direction;the body of each of the first and second leads having a first thicknessand an outer surface at a first height outwardly from the active surfaceof the microelectronic component, the inner length of each of the firstand second leads having a second thickness and a bond surface at asecond height outwardly from the active surface of the microelectroniccomponent, the first thickness being greater than the second thickness,and the first height being greater than the second height; a first bondwire and a second bond wire, the first bond wire electrically coupling afirst terminal of the array of terminals to the bond surface of one ofthe first leads, the second bond wire electrically coupling a secondterminal of the array of terminals to the bond surface of one of thesecond leads, and each of the first and second bond wires having amaximum height outwardly from the active surface of the microelectroniccomponent that is no greater than the first height; a dielectric matrixcovering the first and second bond wires and at least a portion of theinner length of each of the first and second leads, the dielectricmatrix having a maximum height outwardly from the active surface of themicroelectronic component that is no greater than the first height; andan array of conductive structures, each of the conductive structuresbeing carried on and in electrical contact with the outer surface of thebody of one of the first leads or one of the second leads.
 21. Themicroelectronic component assembly of claim 20 wherein each of theconductive structures comprises a solder.
 22. The microelectroniccomponent assembly of claim 20 wherein the body of each of the first andsecond leads has a confronting surface oriented toward the activesurface and the inner length of each of the first and second leads has aconfronting surface oriented toward the active surface, the confrontingface of each body being substantially coplanar with the confrontingsurface of the inner length of the same lead.
 23. The microelectroniccomponent assembly of claim 20 wherein each of the first and second bondwires has a wire diameter and the difference between the first andsecond heights is at least as great as the wire diameter.
 24. Themicroelectronic component assembly of claim 20 wherein each of the firstand second bond wires has a wire diameter and the difference between thefirst and second heights is at least twice the wire diameter.
 25. Themicroelectronic component assembly of claim 20 wherein the first heightis at least 2 mils greater than the second height.
 26. Themicroelectronic component assembly of claim 20 wherein inner ends of thefirst leads are aligned along a first side of the array of terminals andinner ends of the second leads are aligned along an opposite second sideof the array of terminals, defining a terminal gap between the sets ofleads that spans the array of terminals.
 27. The microelectroniccomponent assembly of claim 20 wherein inner ends of the first leads arealigned along a first side of the array of terminals and inner ends ofthe second leads are aligned along an opposite second side of the arrayof terminals, defining a terminal gap between the sets of leads that hasa lateral width of no greater than 35 mils.
 28. The microelectroniccomponent assembly of claim 20 wherein a back surface of themicroelectronic component is exposed.
 29. The microelectronic componentassembly of claim 20 wherein the first bond wire has an exposed lengththat is not covered by the dielectric matrix.
 30. The microelectroniccomponent assembly of claim 20 wherein the dielectric matrix comprises adielectric wire encapsulant and an outer mold compound, the dielectricwire encapsulant covering at least a portion of each of the bond wiresand the outer mold compound covering the wire encapsulant and a portionof each of the leads.
 31. A microelectronic component assemblycomprising: a microelectronic component having an active surface and anarray of terminals carried on the active surface; first and second leadsattached to the active surface of the microelectronic component, each ofthe leads having an elongate body, a reduced-thickness inner length thatis disposed adjacent the terminals of the microelectronic component, andan intermediate length disposed between the body and the inner length,the body having a first thickness and an outer surface at a first heightoutwardly from the active surface of the microelectronic component, theintermediate length having a second thickness and an intermediatesurface at a second height outwardly from the active surface of themicroelectronic component, and the inner length having a third thicknessand a bond surface at a third height outwardly from the active surfaceof the microelectronic component, wherein the second thickness is lessthan the first thickness and greater than the third thickness, andfurther wherein the second height is less than the first height andgreater than the third height; and first and second bond wires, eachbond wire electrically coupling one of the terminals of themicroelectronic component to the bond surface of one of the leads andeach bond wire having a maximum height outwardly from the active surfaceof the microelectronic component that is no greater than the secondheight.
 32. The microelectronic component assembly of claim 31 whereinthe microelectronic component is a first microelectronic component,further comprising a second microelectronic component that includes aback surface and an active surface, the back surface of the secondmicroelectronic component being juxtaposed with the active surface ofthe first microelectronic component at a height outwardly from theactive surface of the first microelectronic component that isintermediate the first and third heights.
 33. The microelectroniccomponent assembly of claim 31 wherein the microelectronic component isa first microelectronic component and the array of terminals is an arrayof first terminals, further comprising: a second microelectroniccomponent that includes a back surface, an active surface, and an arrayof second terminals carried on the active surface, the back surface ofthe second microelectronic component being juxtaposed with the activesurface of the first microelectronic component at a height outwardlyfrom the active surface of the first microelectronic component that isintermediate the first and third heights; a third lead; and a third bondwire that electrically couples one of the second terminals to the outersurface of the third lead.
 34. The microelectronic component assembly ofclaim 31 further comprising an adhesive on the intermediate surface ofeach of the leads.
 35. The microelectronic component assembly of claim31 wherein the microelectronic component is a first microelectroniccomponent, further comprising a second microelectronic component thatincludes a back surface and an active surface, the back surface of thesecond microelectronic component being attached to the intermediatesurface of each of the leads.
 36. The microelectronic component assemblyof claim 35 wherein the back surface of the second microelectroniccomponent is attached to the intermediate surface of each of the leadsby an adhesive.
 37. The microelectronic component assembly of claim 35wherein the back surface of the second microelectronic component isdisposed at a height outwardly from the active surface of the firstmicroelectronic component that is intermediate the first and secondheights and the active surface of the second microelectronic componentis disposed at a height outwardly from the active surface of the firstmicroelectronic component that is greater than the first height.
 38. Themicroelectronic component assembly of claim 31 wherein themicroelectronic component is a first microelectronic component and thearray of terminals is an array of first terminals, further comprising: asecond microelectronic component that includes a back surface, an activesurface, and an array of second terminals carried on the active surface,the back surface of the second microelectronic component beingjuxtaposed with the active surface of the first microelectroniccomponent and attached to the intermediate surface of each of the leadsat a height outwardly from the active surface of the firstmicroelectronic component that is intermediate the first and secondheights; a third lead; and a second bond wire that electrically couplesone of the second terminals to the outer surface of the third lead. 39.A microelectronic component assembly comprising: a first microelectroniccomponent having an active surface that carries a first terminal and asecond terminal; a first lead and a second lead, each of the first andsecond leads being attached to the active surface of the firstmicroelectronic component, each of the first and second leads having: anelongate body having an outer surface at a first height outwardly fromthe active surface of the first microelectronic component; areduced-thickness inner length that is disposed adjacent the terminalsof the microelectronic component, the inner length having a bond surfaceat a second height outwardly from the active surface of the firstmicroelectronic component, the first height being greater than thesecond height; and an intermediate length disposed between the body andthe inner length, the intermediate length having a mounting surface at athird height outwardly from the active surface of the firstmicroelectronic component, the third height being less than the firstheight but greater than the second height; a first bond wireelectrically coupling the first terminal to the bond surface of thefirst lead; a second bond wire electrically coupling the second terminalto the bond surface of the second lead; a second microelectroniccomponent having a back surface oriented toward the active surface ofthe first microelectronic component and an active surface oriented awayfrom the first microelectronic component, the back surface of the secondmicroelectronic component being attached to the mounting surface of theintermediate length of each of the first and second leads; and a thirdbond wire electrically coupling a third terminal carried on the activesurface of the second microelectronic component to a third lead.
 40. Themicroelectronic component assembly of claim 39 wherein each of the firstand second bond wires has a maximum height outwardly from the activesurface of the first microelectronic component that is no greater thanthe third height.
 41. The microelectronic component assembly of claim 39wherein the back surface of the second microelectronic component isjuxtaposed with the active surface of the first microelectroniccomponent at a height outwardly from the active surface of the firstmicroelectronic component that is intermediate the first and secondheights and the active surface of the second microelectronic componentis disposed at a height outwardly from the active surface of the firstmicroelectronic component that is greater than the first height.
 42. Themicroelectronic component assembly of claim 39 wherein the back surfaceof the second microelectronic component is attached to the intermediatesurface of each of the leads by an adhesive.
 43. The microelectroniccomponent assembly of claim 39 wherein the back surface of the secondmicroelectronic component is attached to the intermediate surface ofeach of the leads by an adhesive, the adhesive having a thickness lessthan a difference in thickness between the first thickness and the thirdthickness.
 44. A microelectronic component assembly comprising: firstand second leads, each of the leads having: an elongate body having aninboard section with a first thickness and an outer surface oriented ina first direction; and a reduced-thickness inner length having a secondthickness, a mounting surface oriented in the first direction but spacedfrom the outer surface of the body in an opposite second direction, anda back surface oriented in the second direction, wherein the firstthickness is greater than the second thickness to define a step heightas the difference between the first thickness and the second thickness;a microelectronic component having a back surface, an active surface, anarray of terminals carried on the active surface, and a thicknessbetween the back surface and the active surface that is greater than thestep height, wherein the mounting surface of each of the leads isattached to the active surface of the microelectronic component suchthat the component projects toward the outer surface of the leads; andfirst and second bond wires, each bond wire electrically coupling one ofthe terminals of the microelectronic component to the back surface ofone of the leads and each bond wire having a maximum height outwardlyfrom the active surface of the microelectronic component that is greaterthan the first thickness.
 45. The microelectronic component assembly ofclaim 44 wherein the mounting surface of each of the leads is attachedto the active surface of the microelectronic component by an adhesive.46. The microelectronic component assembly of claim 44 wherein themounting surface of each of the leads is attached to the active surfaceof the microelectronic component by an adhesive, the adhesive having athickness less than the step height.
 47. The microelectronic componentassembly of claim 44 wherein the outer surfaces of the leads aresubstantially coplanar with one another in a first plane and the backsurfaces of the leads are substantially coplanar with one another in asecond plane.
 48. The microelectronic component assembly of claim 44wherein the outer surfaces of the leads are substantially coplanar withone another in a first plane and the back surfaces of the leads aresubstantially coplanar with one another in a second plane, the activesurface of the microelectronic component being positioned between thefirst and second planes and the back surface of the microelectroniccomponent being spaced from the first plane in the first direction. 49.A microelectronic component assembly comprising: first and second leads,each of the leads having: an elongate body having an inboard sectionwith a first thickness and an outer surface oriented in a firstdirection; and a reduced-thickness inner length having a secondthickness, a mounting surface oriented in the first direction but spacedfrom the outer surface of the body in an opposite second direction, anda back surface oriented in the second direction, wherein the firstthickness is greater than the second thickness to define a step heightas the difference between the first thickness and the second thickness;a microelectronic component having a back surface, an active surface, anarray of terminals carried on the active surface, and a thicknessbetween the back surface and the active surface that is greater than thestep height, wherein the mounting surface of each of the leads isattached to the back surface of the microelectronic component and themicroelectronic component projects toward the outer surface of the firstand second leads such that the active surface of the microelectroniccomponent is spaced outwardly in the first direction from the outersurface of each of the leads; and first and second bond wires, each bondwire electrically coupling one of the terminals of the microelectroniccomponent to the outer surface of one of the leads.
 50. Themicroelectronic component assembly of claim 49 wherein the mountingsurface of each of the leads is attached to the back surface of themicroelectronic component by an adhesive.
 51. The microelectroniccomponent assembly of claim 49 wherein the mounting surface of each ofthe leads is attached to the back surface of the microelectroniccomponent by an adhesive, the adhesive having a thickness less than thedifference between the first and second heights.
 52. The microelectroniccomponent assembly of claim 49 wherein the outer surfaces of the leadsare substantially coplanar with one another in a first plane and thebonding surfaces of the leads are substantially coplanar with oneanother in a second plane.
 53. The microelectronic component assembly ofclaim 49 wherein the outer surfaces of the leads are substantiallycoplanar with one another in a first plane and the bonding surfaces ofthe leads are substantially coplanar with one another in a second plane,the back surface of the microelectronic component being positionedbetween the first and second planes.
 54. The microelectronic componentassembly of claim 1 further comprising an adhesive carried by theintermediate surface and configured to support a second microelectroniccomponent.
 55. The microelectronic component assembly of claim 54wherein the maximum height of the first and second bond wires is nogreater than the second height.
 56. The microelectronic componentassembly of claim 39 wherein the back surface of the secondmicroelectronic component is spaced from the active surface of the firstmicroelectronic component to define an intercomponent gap, furthercomprising a dielectric matrix substantially filling the intercomponentgap.